Characterizing momentum transport, dissipative heating, and turbulence structure in the surface layer of landfalling hurricanes using high resolution tower observations

Using high temporal resolution tower observations collected in the 1999-2005 seasons, this study investigates (1) turbulent momentum transport, (2) dissipative heating, and (3) turbulent structure in the surface layer of landfalling hurricanes. Our analyses show that drag coefficient (Cd) during hurricane landfall generally decreases with increasing wind speed and levels off at high wind speeds, consistent with variations of Cd found over ocean conditions. It is found that the dissipative heating rate estimated from Cd and surface mean wind speed, a commonly used parameterization for dissipative heating in models, significantly overestimates the dissipative heating rate directly computed from turbulent velocity spectra. The in-situ tower data reveal the interesting coherent turbulent structures in the surface layer. Such structures have a visible impact on turbulent intensity and momentum transport in the surface layer of landfalling hurricanes.